This invention relates generally to the forming of arbitrary shapes from sheet plastic material and more particularly to a method and apparatus for high volume, high quality cutting of shapes from CD-R, CD-RW, and DVD disks.
Compact discs are flat circular objects having at least one side on which data is recorded and read by laser. Examples of such discs include, CD, CD-R, CD-RW, and DVD discs. The non-recorded side of the disc is typically imprinted with a label identifying the contents of the disc, such as an album cover for a music CD or box-cover art for a DVD-based game. Recently, there has been a market for discs having a non-circular shape. For example, companies have desired that CDs be formed to the approximate size and shape of a business card. Such a disc could be carried around in a person""s wallet, stored with other business cards, include the name of the company imprinted on one side of the card, and yet be capable of holding vast amounts of marketing information on the data portion of the card when read by a proper reader device, such as a computer""s CD-ROM drive.
Because the machinery already exists to apply labels to regular CDs, the label is often applied to the CD prior to the shaping process. It is necessary, therefore, that the CD be shaped in such a fashion so as not to cut off a portion of the label. This requires that disc be properly oriented on the disc machining table prior to cutting.
Prior art machines for cutting CD products into non-circular shapes include a shape cutting device that uses a routing or grinding tool to follow a form which has been machined to the desired shape. Individual CD""s are oriented to the proper rotational location by operators who visually align specially printed marks or machined orientation features on the CD with a reference mark or feature on the machine. Multiple oriented CD""s are placed on top of one another and clamped together. The entire stack is then simultaneously cut into the shape dictated by the form. The shaped CD""s are then unclamped and individually removed from the stack for further packaging. An example of this type of system is found in U.S. Pat. No. 5,882,555.
Several problems occur with the above stated shape forming process. The process requires the design and fabrication of a form which is an extra expense and requires time and resources to complete. The use of a specially printed or machined registration mark requiring human alignment increases product cost and lengthens the manufacturing cycle. Stacking of CD disks requires care to avoid scratching and poses difficulty in generating a smooth cut edge due to the raised spacing ring molded into the bottom surface of each CD. This spacing ring induces a space between adjacent CD""s in the stack which can result in flutter during the cutting process. A clamping device may be used to bend the CD""s and eliminate the spacingxe2x80x94however, this also results in poor quality cut edges.
Accordingly, the need exists for an apparatus and cutting method that overcomes the limitations of the prior art.
It is, therefore, an object of the invention to provide means to easily cut CD""s into a wide variety of shapes at high volume production rates.
Another object of the invention is to provide a means to automatically orient previously printed CD""s using existing label graphics.
Another object of the invention is to provide a method of easily securing the CD into position prior to the shaping operation.
Another object of the invention is to improve the edge quality of the shaped CD.
Another object of the invention is to provide a means to easily change between shape profiles and to create new shape profiles.
An apparatus for cutting CDs constructed according to a preferred embodiment of the invention comprises a large format, gantry type 3-axis CNC mechanism to which multiple high-speed routers are attached. The CNC mechanism consists of accurately controlled closed loop motion in the X, Y, and Z-axes via stepper or servo motor driven ball screws or belt drives. Multiple high-speed router heads are appropriately spaced and attached to the CNC mechanism""s Z-axis. Various types of router bits including single and multiple flute straight or spiral designs may be installed in the router to perform the actual cutting operation. A means for trapping and exhausting cutting debris is attached to the router head.
On the fixed machine frame to which the CNC mechanism is attached, multiple vacuum chuck sites are mounted correspondingly to the multiple router heads. Two vacuum chucks are mounted in close proximity to each router head. Each vacuum chuck consists of an upper plate covered with a resilient, high friction material through which numerous holes are drilled. This plate is mounted to a lower plenum chamber that is connected to a vacuum source. A center mandrel on the upper plate provides registration of the CD to the vacuum chuck. When a CD is placed on the upper plate and the vacuum source activated, the CD is pulled into the resilient material and held in position by the vacuum force and frictional characteristics of the cover material. The resilient material provides a non-destructive path for the router bits to traverse during the cutting operation.
A CD loading and orienting system is attached to the front of the fixed machine frame. This system consists of an elevator mechanism, a 4-axis motion mechanism, and a multiple camera machine vision system.
The elevator mechanism consists of multiple vertical stacks of CDs spaced to correspond with one set of vacuum chucks. CDs are loaded into the elevator on mandrels without regard to orientation of the graphic label printing. Each mandrel stack of CD""s is attached to a Z axis motion control mechanism which moves the stack upward on command and presents the top CD in each stack to a uniform and repeatable height.
The 4-axis motion mechanism consists of an overhead gantry controllable in the X-, Y-, and Z-axes. Multiple CNC rotary axes are attached to the Z-axes. To the rotary axes are attached vacuum gripping devices that when activated provide suction force to pick-up the top CD in each stack. The motion mechanism is sized to provide movement from a position directly over the CD elevator stacks to the vacuum chucks.
The machine vision system consists of multiple cameras mounted on a fixed frame directly above each CD stack in the elevator mechanism. The cameras are connected to a vision processing system that may be integrated with the camera or at a central remote site. On command from the central machine control system, the cameras snap pictures of the top CD in each elevator stack. The machine vision system has been previously trained to identify a specific feature on each products graphic label. This feature need only be a particular element, such as a straight line or other geometric form of the standard graphic, not a special mark applied to the label whose only purpose is for orientation. The orientation of the feature is determined by the vision processing system and the deviation from the desired orientation is calculated. This deviation is translated into a motion command which is sent to each individual rotary axis. Each rotary axis rotates its CD independently so that the graphic label is oriented correctly for proper shape cutting.
In operation, each camera located over a CD snaps a picture, has an angular deviation calculated by the vision processing system, and a motion command transmitted to each rotary axis on the 4 axis motion mechanism. While vision computations are underway, the motion mechanism positions the vacuum gripping devices over each CD stack and picks the top CD in each stack. After the CDs are lifted from the stacks, the vision computed motion command is executed and each CD is independently rotated into the proper orientation for shaping as the motion mechanism moves to place the CDs on the vacuum chucks.
A shaped CD and scrap material unload system is attached to the rear of the fixed machine frame. This system is comprised of a 3-axis motion mechanism, a CD receiving means, and a scrap removal system.
The 3-axis motion mechanism consists of an overhead gantry controllable in the X, Y, and Z axes. To each Z axis are attached vacuum gripping devices that when activated provide suction force to independently pick-up the shaped CD and its associated scrap material in each vacuum chuck location. The motion mechanism is sized to provide movement from a position directly over the vacuum chucks to positions corresponding to shaped CD unload and scrap disposal.
The CD receiving means are vertical mandrels spaced correspondingly to one of a corresponding pair of the vacuum chucks on which the shaped CDs are released. When the mandrel is full, it is removed from the machine for subsequent packaging operations. The scrap material remaining from the cutting operation is deposited in a scrap removal system consisting of a scrap chute which directs the scrap material to the scrap bin located underneath the machine.
In operation, when the CD cutting operation is complete, the machine control system signals the unload motion mechanism to position the vacuum grippers over the shaped CD and scrap material. The shaped CD and scrap material are removed from the vacuum chuck after the chuck releases. The motion mechanism positions the vacuum gripper so that the scrap material is simultaneously deposited in a scrap chute by releasing only that portion of the vacuum gripper. The motion mechanism then locates so that the shaped CD""s are simultaneously deposited on the receiving mandrels.
An alternative embodiment of the invention would be to have the shaped CD automatically inserted into a plastic shipping sleeve and then into a shipping container.
The foregoing and other objects, features and advantages of the invention will become more readily apparent from the following detailed description of a preferred embodiment of the invention that proceeds with reference to the accompanying drawings.